On-Surface Synthesis of 8-and 10-Armchair Graphene Nanoribbons

Armchair graphene nanoribbons (AGNRs) with 8 and 10 carbon atoms in width (8- and 10-AGNRs) are synthesized on Au (111) surfaces via lateral fusion of nanoribbons that belong to different subfamilies. Poly-para-phenylene (3-AGNR) chains are pre-synthesized as ladder ribbons on Au (111). Subsequently, synthesized 5- and 7-AGNRs can laterally fuse with 3-AGNRs upon annealing at higher temperature, producing 8- and 10-AGNRs, respectively. The synthetic process, and their geometric and electronic structures are characterized by scanning tunneling microscopy/spectroscopy (STM/STS). STS investigations reveal the band gap of 10-AGNR (2.0 +/- 0.1 eV) and a large apparent band gap of 8-AGNRs (2.3 +/- 0.1 eV) on Au (111) surface.